Belt training apparatus



March 13, l1962 c. T. LINK, JR., ETAL 3,024,892

BELT TRAINING APPARATUS Filed April 7. 1955 5 Sheets-Sheet 1 March 13, 1962 c. T. LINK, JR., ETAL 3,024,892

BELT TRAINING APPARATUS Filed April 7. 1955 5 Sheets-Sheet 2 YU m1 2 INVENTORS ATTORN S March 13, 1962 c. T. LINK, JR., ETAL 3,024,892

BELT TRAINING APPARATUS Filed April 7. 1955 o Sheets-Sheet 3 March 13, 1962 c. T. LINK, JR., ETAL 3,024,892

BELT TRAINING APPARATUS Filed April 7. 1955 5 Sheets-Sheet 4 INVENTOR. CLM/@L55 7.` .lm/e, c/e.

March 13, 1962 c. T. LINK, JR., ETAL 3,024,892

BELT TRAINING APPARATUS Filed April 7. 1955 5 Sheets-Sheet 5 IN VEN TGRS f/,qeLes 7 L//we de. By @05E/er HMA/cfs @HM/DT ATTORN S United States Patent Otiice @24,892 Patented Mar. 13, i962 3,024,892 BELT TRAINING APPARATUS Charles T. Link, Jr., Skokie, and Robert Francis Schmidt, Elgin, Ill., assignors to Elgin Sweeper Company, Elgin, lill., a corporation of Delaware Filed Apr. 7, 1955, Ser. No. 499,783 2 Claims. (Cl. IMS-202) This invention relates to belt training apparatus and more particularly to apparatus for automatically maintaining a belt in properly trained position over pulleys.

Great difficulties have heretofore been encountered in attempting to train belts over pulleys in that perfect relative positioning of the axes of the pulleys is required to prevent lateral movement of the belt and even the slightest displacement of a pulley axis out of its proper position will result in a substantial lateral movement of the belt as it is driven for any length of time. Furthermore, even if the relative positioning of the pulley axes is absolutely perfect, even a slight stretching or loading of one side of the belt more than the other will cause lateralv displacement. This problem has been very troublesome in the case of belts having a low ratio of length to width, such as conveyor belts, and particularly in the case of conveyor belts for street sweepers which have a width of the same order of magnitude as the length.

Guides have been used to limit lateral movement of belts, but such have not been satisfactory, especially where the belt has abrasive characteristics in which case severe wear of the guides results. It has also been proposed to support the belts on chains or the like trained over suitable sprockets, which will not allow lateral movement. However, this can be very expensive and diiculties have een encountered in securing belts to the chains and properly supporting the belts therefrom.

This invention was evolved with the general object of satisfying a need for a belt training system in which the belt is automatically maintained in properly trained position.

In the belt training system of this invention, means are provided for automatically adjusting the position of a belt on pulleys or rollers to maintain the belt in properly trained position thereon. Such means preferably does not act directly on the belt itself but, according to an important feature of this invention, the position of the axis of one pulley or roller is adjusted relative to the position of another pulley or roller. If, for example, the belt should move slightly out of its proper position, the position of the axis of one pulley or roller is adjusted and with further drive of the belt, it will move into its proper position. Accordingly, the adjustment is achieved through the normal coaction of the belt and pulleys, and it is not necessary to apply a direct lateral force to the belt.

In accordance with another important feature of the invention, the adjustment means are controlled by means which sense the position of one or both edges of the belt. Preferably, the sensing means may act at only one edge of the belt and responds to lateral movement of the belt in both directions.

In accordance with a specific feature of the invention, means are provided for supporting at least a pair of pulleys or rollers from a suitable frame including bearing means journalling one end of one of the rollers and arranged for movement relative to the frame to adjust the position of the axis of such one roller relative to the other, movement of such bearing means being so controlled as to automatically maintain the belt in proper position on the rollers. Preferably, drive means are provided with act at the other end of such one of the rollers. This insures proper control of the belt position, since the roller that drives the belt will have sufiicient engagement with the belt to control the position thereof, when the axis of such roller is adjusted. Also, the construction is simplified because the drive and control means act on only one roller, and conventional bearing supports may be used for the other roller or rollers.

A further specic feature of the invention is in the construction of the sensing means. In accordance with this feature, a follower is urged into engagement with one edge of the belt, preferably adjacent movable bearing means such as above described, movement of the follower in either direction being used to effect compensating movement of the belt position adjustment means.

A further specific feature of the invention is in a servo mechnism used for automatically controlling the belt position.

In accordance with another feature of the invention, the automatic belt positioning arrangement of this invention is embodied in a street sweeper which includes a broom for throwing refuse forwardly and upwardly on forward travel of the sweeper, a dirt box assembly at the forward end of the sweeper and a conveyor for receiving refuse from the broom and carrying it upwardly and forwardly for discharge into the dirt box assembly. The conveyor comprises lower and upper rollers with a conveyor belt trained thereover, which belt may be of a flexible material such as a rubber-like material. The width of the belt approaches that of the sweeper, and the belt need have a length approximating the width of the sweeper, so that the ratio of belt length to belt width is very low, Because of this fact, and because of flexibility of the belt, it would be extremely diiiicult to maintain the belt in proper position on the rollers, without the automatic control system of this invention.

The street sweeper conveyor is preferably driven by drive means acting at one end of the upper roller, with bearing means at the other end of the upper roller being moved to adjust the position of the belt on the rollers.

In accordance with a further feature of the invention, the street sweeper includes a pair of frame structures extending upwardly and forwardly along opposite sides of the sweeper with means journalling the lower conveyor roller between lower end portions of such frame structures and with means journalling the upper roller between upper end portions of the frame structures and arranged to automatically maintain the belt in properly trained position on the rollers, the frame structures being supported in the sweeper for pivotal movement about a horizontal axis intermediate the axes of the rollers to move the lower end of the conveyor between a lower operative position and an upper inoperative position. The belt position adjusting arrangement of this invention is especially suited for this combination, because it is readily installed on such pivotal frame structures.

In conveyors generally, and particularly in street sweeper conveyors, dirt or other extraneous matter is apt to find its way into the space within the conveyor belt to accumulate around the lower pulley or roller of the conveyor. A certain amount of such dirt will cling to the lower roller and after a period of time it will build up thereon to effectively enlarge the roller, usually in a nonuniform manner from one end to the other. To divert dirt away from the lower roller, a flexible scraper element is provided which is biased into engagement with the inside upwardly facing surface of the conveyor belt. In addition, a xed knife element is preferably provided inside the belt adjacent the surface of the lower roller to limit accumulation of dirt thereon. With this arrangement, dirt falling into the space within the belt can have no deleterious effects.

A specific object of the invention, accordingly, is to provide an improved belt training system in which the relative positions of the axes of belt training rollers are automatically adjusted to maintain a belt in proper position.

Another object of the invention is to provide an irnproved belt training system in which means for sensing the position of at least one edge of a belt are utilized for automatically adjusting the position of a belt to maintain it in proper position on pulleys or rollers.

Another object of the invention is to provide an improved street sweeper including means for automatically maintaining a conveyor belt in proper position on rollers.

A still further object of the invention is to provide an improved conveyor for street sweepers or the like with means for preventing deleterious effects due to dirt or the like falling into the space within a conveyor belt.

This invention contemplates other and more specific objects, features and advantages which will become more fully apparent from the following detailed description taken in conjunction with the accompanying drawings which illustrate a preferred embodiment and in which:

FIGURE l is a side elevational view of a street sweeper incorporating the conveyor and belt training apparatus of this invention;

FIGURE 2 is a sectional view taken substantially along line l'I-II of FIGURE l to illustrate in plan the conveyor and belt training apparatus of this invention;

FIGURE 3 is a sectional view taken substantially along line III-III of FIGURE 2;

FIGURE 4 is a sectional view taken substantially along line IV-IV of FIGURE 2;

FIGURE 5 is a sectional view taken substantially along line V-V of FIGURE 2;

FIGURE 6 is a sectional view taken substantially along line VI-VI of FIGURE 2;

FIGURE 7 is an end elevational view of a portion of the belt control mechanism, looking from substantially along line VII-VII of FIGURE 2; and

FIGURE 8 is a sectional view taken substantially along line VIII-VIII of FIGURE 6.

Reference numeral 10 generally designates a street sweeper constructed according to the principles of this invention which may include a pair of front wheels 11, a single steerable rear wheel 12, a dirt box assembly 13 at the forward end of the sweeper, a gutter or side broom assembly 14 for throwing refuse out from a street curb into the path of a main broom 15 which throws refuse forwardly onto an inclined conveyor 16 which moves the refuse forwardly and upwardly to discharge the same into the dirt box 13 from which it may be periodically removed.

This invention is considered with the construction and operation of the conveyor structure 16, the general layout of which is illustrated in the plan view of FIGURE 2. Referring thereto, a conveyor belt 17, which may be of a heavy flexible material, such as a rubber-like material, is trained over the lower pulley or roller 18 and an upper pulley or roller 19. In order to show the parts as clearly as possible, an intermediate section of the belt 17 is not shown in FIGURE 2, so that this figure does notY show the actual relation of belt length to belt width. Actually, the belt width may be -of the same order of magnitude as the belt length. With a belt of such dimensions, and particularly if the belt is of a flexible material, it is extremely difcult to maintain the belt in proper position on the rollers, because even a very slight displacement of the axis of one roller out of its proper position will result in lateral movement of the belt as it is driven, and after any substantial length of time the belt will move into engagement with structures at one side of the assembly or the other.

According to this invention, a mechanism generally designated by reference numeral is provided at one end of the upper roll 19 and is arranged to sense the position of one edge of the belt and so control the position of the axis of the roller 19 as to automatically maintain the belt 17 in a proper position on the rollers. This mechanism 20 will, of course, be described in detail hereinafter.

At the other end of the upper roll 19, a bearing and drive mechanism 21 is provided. The control mechanism 20 and the drive mechanism 21 are supported from a pair of frame structures 22 and 23 which extend upwardly and forwardly just inside side Walls 24 and 25 of the street sweeper 10, the lower roller 18 being journalled between the lower end portions of the frame structures 22 and 23.

The frame structures 22 and 23 may each have a generally channel-like form and may carry plates 26 and 27 which extend from the side walls 24 and 25 over edge portions of the belt 17 and are inclined so as to permit ow of dirt or refuse thrown thereon down onto the belt 17. It might here be noted that the belt 17 is preferably provided with laterally extending longitudinally spaced ribs, not shown, to more efficiently carry dirt and refuse upwardly.

When the street sweeper 10 is in operation, the lower end of the conveyor 16 should be positioned relatively close -to the surface of the street so that the maximum amount of dirt thrown forwardly by the main broom 15 will be carried away by the conveyor 16. However, during travel of the sweeper 10 to or from a location where the sweeping is to be accomplished, it is desirable that the lower end of the conveyor 16 be elevated. For this purpose, the frame structures 22 and 23, and the structures carried thereby, `are supported for pivotal movement about a horizontal axis intermediate the axes of the rollers 18 and 19, by means of a pair of stub shafts 28 and 29 respectively secured to the frame structures 22 and 23 and journalled in suitable `socket members 30 and 31 secured to the side walls 24 and 25 of the sweeper 4v10.

For effecting pivotal movement of the frame structures 22 and 23 4to move the lower end of the conveyor 16 between a lower operative position and Ian upper inoperative position, a pair of uidactuated assemblies 32 and 33 act between the body of the street sweeper and the frame structures 22 and 23, respectively. The fluid-actuated assembly 33 may, asbest illustrated in FIGURE 4, cornprise a cylinder 34 having a lug 35 rigidly secured thereto, the lug 35 being disposed between spaced portions 36 and 37 of a bracket 3S rigidly secured to means secured to the side wall 25 with a pin 39 extending through the portions 36 and 37 of the bracket 38 and through the lug 35 so as to pivotally secure the cylinder 34 to the sweeper body. A piston 40 `is movable in `the cylinder 34 and a shaft 41 secured to the frame structure 23 extends through the upper end of Kthe piston 40 so as to pivotally secure the support structure 23 thereto. By introducing iluid into the cylinder 34, the piston 40 will be elevated to elevate the lower end of the conveyor 16.

The fluid-actuated assembly 32 is preferably substanftially identical to the assembly 353 and the cylinders of the two assemblies are preferably connected to a common iiuid supply line so that balanced forces will be exerted by the two assemblies.

The opposite ends of `the lower roller may be journalled in bearings which are fixed with respect to the frame structures 22 and 23. Preferably, however, the bearing support for one end of the lower roller is adjustable when a belt is originally installed to compensate for inaccuracies in the manufacture of the belt and other elements. In particular, the support of the right-hand end of the roller 18, as viewed in FIGURE 2, may be adjusta- `ble through an arrangement illustrated in the enlarged cross-sectional view of FIGURE 3. Referring thereto, the roller 18 yhas a protruding shaft portion 42 which is disposed in a notch 43 of a plate 44, the shaft portion 42 having an annular groove 45 therein of a width partially equal tothe thickness of the plate 44, so as to limit axial movement of the roller 18 relative to the plate 44.

The plate 44 may be secured in depending relation to a plate 46 which is secured flat against the underside of the frame structure 23. To hold the plate 46 against the frame structure 23, a pair of bolts 47 and 48 are provided which extend through washers49 and 50, slots 51 and 52 aoaasean in the plate 46 and threaded apertures in the frame structure 23, nuts 53 and 54 being preferably welded or otherwise secured on the top face of the frame structure 23 to provide increased strength.

To adjust the position of the right-hand end of the roller 18, the bolts 47 and 48 may be slightly loosened and a screw 55 may be rotated, the screw 55 extending through a depending lug 56 on the frame structure 23 into engagement with a depending flange portion 57 of the plate 46. After the desired adjustment is effected, a nut 58 on the screw 55 may be tightened into engagement with the lug 56 to lock the screw 55 in position, and the screws 47 `and 4S may be tightened to lock the plate 46 against the underside of the frame structure 23.

It is virtually impossible to prevent dirt from finding its way into the space within the belt 17. Such dirt would normally fall into a trough-like region defined by the inside upwardly facing surface 59 of the belt 17 and the portion of the lower roller 18 in facing relation thereto and, as the belt is driven, such dirt would be pressed against the surface of the lower roller 18 to build up on the roller and produce deleterious results.

To divert dirt away from this region, a scraper element 60 is provided which extends for substantially the full width of the belt 17 and is preferably of a flexible material, such as a rubber-like material, biased into engagement with the inside upwardly facing surface 59 of the belt 17.

In addition, a knife element 61 is provided which extends for substantially the full length of the roller 18 and has an edge 62 closely adjacent the surface of t-he roller 18, to prevent buildup of dirt thereon.

To support the scraper element 60, the lower edge portion thereof may be secured against the surface of a flange portion 63 of a bracket 64, by means of stud bolts 65 on `the flange 63 extending through suitable apertures in the element 60, nuts 66 being threaded on the bolts 65 with washers 67 preferably provided between the nuts 66 `and the element 60.

The bracket 64 may be rigidly secured against a plate 68 extending for substantially the full wid-th of the belt 17, and the ends of the plate 68 may be supported from the protruding shaft portions of the roller 18, including the right-hand end shaft portion 42 referred to above. For this purpose, a carrier 69 is journalled on the shaft portion 42 inside the plate 44 and has an outwardly projecting flange portion 70 against which the plate 68 is secured by a screw 71. A similar support may be provided at the other end of the roller 18. The knife 61 may be carried by a plate 72 secured between the head of the bolt 71 and the plate 68.

For support of .the right-hand end of the upper roller 19, it is ailixed to a plate 73 which is removably secured by bolts 74 to a plate 75 which, in turn, is secured by suitab-le means to a shaft journalled for rotation in a housing 77 of the drive assembly 21 with thrust bearings being provided to prevent axial movement of such shaft. Such shaft may carry a worm wheel meshed with a worm which is coupled to the shaft of a fluid-actuated drive motor 78 mounted on the casing or housing 77, as shown in FIGURE 5. Such shafts, bearings and the worm and worm wheel are not shown, but may take any desired form.

To support the housing 77 of the drive -assembly 21, it has a pair of spaced lugs 79 and 80 which are journalled on opposite ends of a pin 81 carried by a sleeve 82 between the lugs 79 and 80, the sleeve 82 being rigidly secured to the end of a shaft 83 which is journalled in a sleeve 84 carried by the frame structure 23. This arrangement thus provides a universal coupling with the housing 77 being rotatable about the axis of the pin 81 and about the axis of the shaft 83.

For adjusting the position of the shaft 83 and hence the support assembly 21, a rod 85 is provided which has an end portion threaded into a lower end wall portion 86 of the sleeve 84, to engage the lower end of the shaft 83. The rod has a head 87 which may be rotated to adjust the position of the assembly 21, the rod 85 having a substantial length, as illustrated in FIGURE 2, to permit ready access to the head 87 thereof.

The left-hand end of the upper roller 19, as viewed in FIGURE 2, has a protruding shaft portion 88 which is journalled in a suitable bearing assembly 89, the bearing assembly 89 being flexibly connected through a coupling structure 90 to the end of a cylindrical piston 91 which is movable in a cylinder 92 rigidly supported in the frame structure 22. Fluid under pressure, such as oil, may flow into the cylinder 92 through a conduit 93 to actuate the piston 91 and force the bearing assembly 89 in a direction away from the lower roller 18, or the fluid may be allowed to flow out of the cylinder 92 through the conduit 93 to allow the bearing assembly 89 to move toward the lower roller 18. Thus, by control of fluid flow to or from the cylinder 92, the position of the axis of the upper roller 19 may be adjusted relative to the position of the axis of the lower roller 18.

It will be appreciated that movement of the left-hand bearing assembly 89 away from the lower roller 18 will tend to effect movement of the belt 17 laterally to the right as it is driven, while movement of the bearing assembly 89 toward the lower roller 18, the belt 17 will tend to move to the left as it is driven. Accordingly, by proper control of the position of the bearing assembly 89, the belt 17 can be maintained in proper position on the rollers 18 and 19.

To control flow of fluid to the cylinder 92 and thus control the position of the bearing assembly 89 and the position of the belt 17, a control valve 94 is connected to the conduit 93 and through a conduit 95 to a fluid reservoir and through a conduit 96 to a pump or other source of fluid under pressure, the reservoir and pump being not shown, since any conventional reservoir and pump can be utilized.

The control valve 94 may preferably comprise a body 97 secured by bolts 98 on a plate 99 which is rigidly secured to a bar 100 secured to the frame structure 22. The valve body 97 has a cylindrical bore 101 closed at opposite ends by end plates 102 and 103, and a valve member 104 is movable in the bore 101, the valve member 104 having an actuating rod portion 105 projecting through the end plate 103 with a coiled compression spring 106 acting at the other end of the valve member 104.

The valve member 104 is provided with spaced reduced `diameter portions 107 and 108 with a portion 109 therebetween in sealing engagement with the internal surface of the bore 101. With the valve 104 in a neutral position as illustrated in FIGURE 8, the portion 109 will close off an annular groove 110 in the valve body 97 about the bore 101. When the valve member 104 is moved to the right from the position illustrated in FIGURE 8, communication will be established between the annular groove 110 and a port 111 communicating with the bore 101, while when the valve member 104 is moved to the left from the position shown in FIGURE 8, communication will be established between the groove 110 and a port 112. Thus, by movement of the valve member 104, the groove 110 is selectively connected to the port 111 or the port 112. The groove 110 communicates through a passage not shown with the conduit 93; the port 111 communicates through a passage 113 with the conduit 9S and the port 112 communicates through a passage 114 with the conduit 96, the conduits 95 and 96 being in cornmunication respectively with a reservoir and source of fluid pressure as previously indicated, so that with movement of the valve member 104 to the left as viewed in FIGURE 8, the conduit 93 will communicate with the source of fluid pressure while with movement of the valve member 104 to the right, the conduit 93 will communicate with the reservoir.

It may be noted that any fluid that might leak past 7 the valve member 104 into the space between the valve member 104 and the end plate 103 might block operation of the valve and hence a suitable drain (not shown) is provided for such spaces.

According to an important feature of the invention, the position of the bearing assembly 89 is controlled, through the valve 94, from means which sense the position of the edge of the belt 17. In particular, a follower in the form of a roller 115 is engaged with the edge of the lower portion of the belt 17 adjacent the lett-hand end of the upper roller 19, the roller 115 being rotatably journalled on a pin 116 which is carried on the end of an arm 117 of a lever 118. A plate 119 may project inwardly from the lever arm 117 under the roller 115 to aid in insuring engagement of the edge of the belt 17 with the roller 115 in initial assembly of the parts.

The lever 118 has a second arm 120, the arms 117 and 120 being in the form of bars welded or otherwise rigidly secured together, the lever 118 being carried from a sleeve portion 121 of a bracket 122 having a base portion 123 secured by bolts 124 to the underside of the bar 100 and connected to the sleeve portion 121 through a curved arm 125. To journal the lever 118 on the sleeve portion 121, a bolt 126 has a lower head portion 127 and a shank portion 128 extending upwardly through the sleeve 121 and threaded into the lever 118, washers 129 and 130 being preferably provided between the lever 118 and the sleeve portion 121 and between the sleeve portion 121 and the head 127 of the bolt 126.

The end of lever arm 120 is pivotally connected to one end of a link 131 through a bolt 132 having a shank portion 133 extending through a washer 134, the link 131, a spacer 135 secured to the underside of the link 131, a second washer 136 and the lever arm 120, there being a threaded engagement between the shank portion 133 and the lever arm 120.

The other end of the link 131 is pivotally connected to an intermediate portion of a lever 137 by means of a bolt 138 having a lower head portion 139 and a shank portion 140 extending upwardly through a washer 141, a spacer sleeve 142, the link 131, a washer 143 and the lever 137, there being a threaded interengagement between the shank portion 140 and the lever 137. The sleeve 142 rides in a slot 144 in the support plate 99 to guide the link 131 in movement.

One end of the lever 137 is engaged with the end of the rod portion 105 of the valve member 104, and the other end thereof is engaged with the end of an adjustment screw 145 which is threaded through a lower portion 146 of the housing of the bearing assembly 89.

Operation Referring particularly to FIGURE 8, if the conditions effec-ting the position of the belt 17 are changed in a manner such that the edge of the belt 17 moves toward the valve 94, the lever 118 will be pivoted in a clockwise direction about the axis of bolt 126 to move the bolt 132 to the left and thereby move the link 131 to the left. The link 131 will act through the bolt 138 to pivot the lever 137 about the end of the adjustment screw 145 and move the valve member 104 to the left against the force of the spring 106. When the valve member 104 is moved to a suicient extent, communication will be established between the groove 110 and the port 112 to establish communication between the conduit 96, which is connected to a source of fluid pressure, and the conduit 93, which is connected to the cylinder 92.

Fluid under pressure entering the cylinder 92 will force the piston 91 upwardly to move the bearing assembly 89 upwardly. With continued drive of the belt 17, it will tend to move to the right as viewed in FIGURE 2, away from the valve 94, and when it has moved to a certain extent, the valve member 104 will move back to its neutral position as illustrated in FIGURE 8, under the actuating force of lthe spring 106.

If the belt 17 moves too far to the right as viewed in FIGURE 2, away from the valve 94, the lever 118 will move in a counter-clockwise direction to move the link 131 to the right and allow the lever 137 to pivot in a counter-clockwise direction about the end of the actuating screw 145 under the force of the spring 106.

When the valve member 104 moves to a certain extent to the right, communication will be established between the groove and the port 111 to establish communication between the conduit 95, which is connected to a reservoir, and the conduit 93 connected to the cylinder 92. This will allow the piston 91 to move downwardly to move the bearing assembly 89 downwardly and with continued drive of the belt 17 it will tend to move to the left as viewed in FIGURE 2 and through the lever 118, link 131 and lever 137 move the valve member 104 back to its neutral position.

Accordingly, the belt 17 is automatically maintained in proper position on the rollers 18 and 19.

It should be noted that the position of the valve member 104 is effected not only by the position of the follower roller but is also etfected by the position of the bearing assembly 89 relative to the frame structure 22, since the position of the lever 137 is determined by the position of the end of the adjustment screw 1,45 which is carried by the housing of the bearing assembly 89. This is an advantage, because it permits more rapid response of the regulating system, without overshoot and oscillations. In particular, if the belt 17 moves to the left, as viewed in FIGURE 2, the valve member 104 will be moved to the left to connect the cylinder 92 to the source of uid pressure and move the bearing assembly 89 upwardly, or to the left as viewed in FIGURE 8. This movement of the bearing assembly 89 will be relative to the valve 94, since the valve is supported from the frame structure 22, and the lever 137 will immediately pivot in a counterclockwise direction as viewed in FIGURE 8 to allow the valve member 104 to move to the right under the force of the spring 106 to its neutral position and thereafter, from the movement of the bearing assembly 89 and drive of the belt 17, the belt will move to the right, as viewed in FIGURE 2, to initiate a new cycle of operation. Accordingly, the valve and associated fluid system can be arranged to give very rapid response, and because of the neutralizing action obtained through the lever 137, the valve member 104 can be immediately moved toward its neutral position and does not need to wait for the effect on the position of the belt 17, so that overshoot, or oscillations, are prevented.

The screw also serves as a means for adjusting the position of the belt 17 on the rollers 18 and 19. Usually, of course, the screw 145 is adjusted to position the belt in centered relation relative to the rollers 18 and 19. It will be noted that the belt training system is very flexible and any belt (of length within a wide range) can be used and maintained in proper relation on the rollers 18 and 19. In the initial installation of any belt, the screw 145 is adjusted to position the upper end of the belt in desired relation, usually centered, on the upper roller 19, the screw 87 is adjusted to obtain the desired tension in the belt, and the screw 55 is adjusted to obtain the desired position of the lower end of the belt relative to the lower roller 18, when the belt is properly positioned on the upper roller 19. As a belt is used, it will usually stretch to a certain extent, and it may become necessary to adjust the screw 87 to obtain optimum tension in the belt. With substantial adjustment of the screw 87, it will be necessary to readjust the screw 145 to obtain the desired relation of the belt to the upper roller.

It will, accordingly, be appreciated that this invention provides a belt training system in which a belt is automatically maintained in proper relation on pulleys or rollers, the system being particularly advantageous in the street sweeper application as disclosed.

It will be understood that modifications and variations may be effected without departing from the spirit and scope of the novel concepts of this invention.

We claim as our invention:

1. In a belt training and aligning system, an idler pulley, a drive pulley, a belt trained about said pulleys, bearing means journalling said pulleys for rotation about horizontal axes, the bearing means for said drive pulley including a pivoted bearing support mounted for move ment about an axis perpendicular to the axis of rotation of said drive pulley and a translationally movable bearing support mounted for movement toward and from said idler pulley, and means for maintaining said belt in alignment With respect to the faces of said pulleys comprising a `cylinder and piston having operative connection with said translationally movable bearing support for moving said drive roller about the axis of movement of said pivoted bearing support, a valve controlling the supply of uid under pressure to said cylinder and piston including a valve -body having a stem extending outwardly therefrom and a spring biasing said stem in extended relation with respect to said valve body, means for operating said valve in accordance rwith the position of said belt on said pulleys comprising a lbellcrank pivoted adjacent said drive pulley, a feeler roller on one arm thereof engageable With the edge of the belt, a link pivoted to fthe other arm of said bellcrank, a lever pivorted to said link intermediate the ends of said lever, an abutment engaging one end of said lever and an engaging connection `between the other end of said lever and said valve stern whereby said spring biases said roller into engagement with the edge of fthe belt to effect operation of said valve in accordance with the position of said belt on said drive pulley.

2. A belt training and aligning system in accordance with claim 1 in which the abutment for the lever pivoted to the link is adjustable to effect pivotal movement of said lever and bellcrank and the adjustment of the position of said belt on said pulley.

References Cited in the le of this patent UNITED STATES PATENTS 689,881 Hoy Dec. 31, 1901 1,118,559 Lambert Nov. 24, 1914 1,416,041 Liddell May 16, 1922 1,933,485 Rund et al. Oct. 31, 1933 1,974,826 Low Sept. 25, 1934 2,709,588 Staege May 31, 1955 2,724,492 Kolbe Nov. 22, 1955 2,751,067 Nicholson June 19, 1956 2,777,331 Cruickshanks lan. 15, 1957 FOREIGN PATENTS 665,050 Great Britain Jan. 16, 1952 

